New York Mets ace Matt Harvey speaks during a news conference Monday announcing that he has been diagnosed with a partially torn ligament.

NEW YORK — Matt Harvey has a partially torn ligament in his right elbow, a potentially devastating injury for the pitcher that had given the foundering New York Mets reason to be hopeful about its future.

For now, the 24-year-old Harvey and the Mets hope that he will be able to avoid reconstruction surgery on the ulnar collateral ligament. A full prognosis will not be made until swelling in the elbow goes down in about two weeks.

“It was tough. Obviously it was the last thing I was expecting when I went this morning,” Harvey said Monday. “I am going to do everything I can to avoid surgery.”

The National League’s All-Star game starter on his home field this July, Harvey has been experiencing forearm tenderness for some time but he could not pinpoint exactly when it began. The discomfort increased during his start Saturday against the Detroit Tigers, when he allowed a career-high 13 hits.

Harvey admitted he was tired against the Tigers, the 26th start of his first full season in the major leagues, and manager Terry Collins said he noticed Harvey’s pitches weren’t as crisp, a sign of fatigue.

But Collins didn’t know Harvey had any issues with his forearm until Sunday and the ace went for an MRI at the Hospital for Special Surgery a day later.

“Nothing is shooting in my elbow at all. That’s not the issue,” Harvey said. “When I heard the news, I was pretty shocked. I’m still very optimistic.”

Harvey wasn’t the only one in the Mets organization stunned by the news.

“This was a surprise to all of us,” general manager Sandy Alderson said. “Forearm pain can foretell problems with the elbow, but in this particular circumstance there had been no indications of that.”

The seventh pick overall of the 2010 draft, Harvey is 9-5 with a 2.27 ERA. He has a league-leading 191 strikeouts in 178 1-3 innings pitched and was a top candidate for the NL Cy Young Award.

The Mets were working on limiting Harvey’s innings to a little more than 200 this season. Alderson said there is no real scientific basis for managing young pitchers’ careers.

“These innings limits are not a guarantee of anything. They’re certainly not based on any science,” Alderson said. “This is a kind of progressive injury that isn’t a function of, we don’t believe in this case a specific incident or quote overuse. It’s an anatomical fact that these things happen.”